U.S. patent application number 11/838227 was filed with the patent office on 2009-02-19 for light generating layer for a reflective display.
This patent application is currently assigned to MOTOROLA, INC.. Invention is credited to XiaoPing Bai, Sen Yang, Wenyong Zhu.
Application Number | 20090045722 11/838227 |
Document ID | / |
Family ID | 40362409 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090045722 |
Kind Code |
A1 |
Bai; XiaoPing ; et
al. |
February 19, 2009 |
LIGHT GENERATING LAYER FOR A REFLECTIVE DISPLAY
Abstract
A self emission device (644) that emits light (526). The self
emission device can include at least one light emission layer (104)
encompassing an area, and generating light over such area in a
distributed fashion. The self emission device also can include a
first electrode (113) interfacing with a first side (116) of the
light emission layer and a second electrode (114) interfacing with
a second side (117) of the light emission layer. The first
electrode and the second electrode can provide energy used by the
light emission layer to illuminate. The self emission device can be
a component of a display (100) comprising a reflective display
panel (102).
Inventors: |
Bai; XiaoPing; (Lake Zurich,
IL) ; Yang; Sen; (Palatine, IL) ; Zhu;
Wenyong; (Lindenhurst, IL) |
Correspondence
Address: |
CUENOT & FORSYTHE, L.L.C.
12230 FOREST HILL BLVD., SUITE 120
WELLINGTON
FL
33414
US
|
Assignee: |
MOTOROLA, INC.
Schaumburg
IL
|
Family ID: |
40362409 |
Appl. No.: |
11/838227 |
Filed: |
August 14, 2007 |
Current U.S.
Class: |
313/504 ;
445/23 |
Current CPC
Class: |
G02F 1/133616 20210101;
G02F 1/1336 20130101; G02F 2203/02 20130101; H01J 1/70 20130101;
H01L 27/3232 20130101 |
Class at
Publication: |
313/504 ;
445/23 |
International
Class: |
H01L 51/52 20060101
H01L051/52; H01J 1/62 20060101 H01J001/62; H01J 9/02 20060101
H01J009/02 |
Claims
1. A display, comprising: a reflective display panel on which
visual information is presented; and at least one light emission
layer disposed in front of the reflective display panel, the light
emission layer encompassing an area substantially congruent with at
least a visible portion of the display panel, and generating light
over such area in a distributed fashion.
2. The display of claim 1, further comprising: a first electrode
interfacing with a first side of the light emission layer; and a
second electrode interfacing with a second side of the light
emission layer; wherein the first electrode and the second
electrode provide energy used by the light emission layer to
illuminate.
3. The display of claim 2, wherein the light emission layer is
arranged in an illumination pattern.
4. The display of claim 3, wherein the light emission layer
comprises at least one component selected from the group consisting
of a light emitting diode and an organic light emitting diode.
5. The display of claim 3, wherein the first electrode comprises at
least one electrical conductor and is arranged in the illumination
pattern.
6. The display of claim 5, wherein the first electrode is
positioned to reflect light generated by the light emission layer
toward the reflective display panel.
7. The display of claim 3, wherein the second electrode comprises
at least one transparent conductor arranged in the illumination
pattern.
8. The display of claim 2, wherein at least one of the first and
second electrodes comprises a transparent conductor.
9. The display of claim 1, further comprising a light diffusion
layer.
10. The display of claim 9, wherein the light diffusion layer is
disposed in front of the light emission layer.
11. A self emission device that emits light, comprising: at least
one light emission layer encompassing an area, and generating light
over such area in a distributed fashion; a first electrode
interfacing with a first side of the light emission layer; and a
second electrode interfacing with a second side of the light
emission layer; wherein the first electrode and the second
electrode provide energy used by the light emission layer to
illuminate.
12. The self emission device of claim 11, wherein the light
emission layer is arranged in an illumination pattern.
13. The self emission device of claim 12, wherein the first
electrode comprises a plurality of electrical conductors arranged
in the illumination pattern.
14. The self emission device of claim 13, wherein the first
electrode is positioned to reflect light generated by the light
emission layer toward a particular side of the self emission
device.
15. The self emission device of claim 12, wherein the second
electrode comprises a transparent conductor arranged in the
illumination pattern.
16. The self emission device of claim 11, wherein at least one of
the first and second electrodes comprises a transparent
conductor.
17. A method of manufacturing a self emission device, comprising:
depositing a first electrode on a first substrate; depositing a
light emission layer on the first electrode, the light emission
layer encompassing an area over which light is to be generated in a
distributed fashion; and depositing a second electrode on the light
emission layer.
18. The method of claim 17, further comprising: positioning a
second substrate over the second electrode.
19. The method of claim 18, wherein depositing the first electrode
on the first substrate comprises depositing the first electrode on
a substrate that is transparent.
20. The method of claim 18, wherein depositing the first electrode
on the first substrate comprises depositing the first electrode on
a substrate that is translucent.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to electronic
displays and, more particularly, to reflective displays.
[0003] 2. Background of the Invention
[0004] A reflective display is a display that includes a reflective
surface from which visual information is presented. There are a
number of reflective display technologies known in the art,
examples of which include a reflective liquid crystal display
(LCD), an electrophoretic display (EPD), a reflective type thin
film transistor display, a flip-dot display, and so on.
[0005] Rather than using backlighting for illumination like an
emissive electronic display, a reflective display typically relies
on ambient light. Thus, a reflective display generally requires
less power to operate in comparison to an emissive electronic
display. Moreover, a reflective display can be made to be very
thin. Indeed, EPDs oftentimes are considered prime examples of the
electronic paper category of displays because of their paper-like
appearance. Notwithstanding, although reflective displays are
typically well suited for use in sunlight or in bright indoor
lighting, they typically do not perform well in low-light
conditions.
SUMMARY OF THE INVENTION
[0006] The present invention relates to a display which includes a
reflective display panel on which visual information can be
presented. The display also can include at least one light emission
layer disposed in front of the reflective display panel. The light
emission layer can encompass an area substantially congruent with
at least a visible portion of the display panel, and generate light
over such area in a distributed fashion.
[0007] The display further can include a first electrode
interfacing with a first side of the light emission layer and a
second electrode interfacing with a second side of the light
emission layer. The first electrode and the second electrode can
provide energy used by the light emission layer to illuminate.
[0008] The light emission layer can be arranged in an illumination
pattern. The light emission layer can include at least one
component selected from the group consisting of a light emitting
diode and an organic light emitting diode. The first electrode can
include at least one electrical conductor and can be arranged in
the illumination pattern. The first electrode can be positioned to
reflect light generated by the light emission layer toward the
reflective display panel. In another arrangement, the first
electrode can include a transparent conductor. Further, the second
electrode can include at least one transparent conductor arranged
in the illumination pattern.
[0009] The display further can include a light diffusion layer. The
light diffusion layer can be disposed in front of the light
emission layer.
[0010] The present invention also relates to a self emission device
that emits light. The self emission device can include at least one
light emission layer encompassing an area, and generating light
over such area in a distributed fashion. The self emission device
also can include a first electrode interfacing with a first side of
the light emission layer and a second electrode interfacing with a
second side of the light emission layer. The first electrode and
the second electrode can provide energy used by the light emission
layer to illuminate.
[0011] The light emission layer can be arranged in an illumination
pattern. The first electrode can include a plurality of electrical
conductors arranged in the illumination pattern. The first
electrode can be positioned to reflect light generated by the light
emission layer toward a particular side of self emission device. In
another arrangement, the first electrode can include a transparent
conductor. Further, the second electrode can include a transparent
conductor arranged in the illumination pattern.
[0012] The present invention also relates to a method of
manufacturing a self emission device. The method can include
depositing a first electrode on a first substrate. The substrate
can be transparent or translucent. The method also can include
depositing a light emission layer on the first electrode. The light
emission layer can encompass an area over which light may be
generated in a distributed fashion. Further, a second electrode can
be deposited on the light emission layer. The method also can
include positioning a second substrate over the second
electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Preferred embodiments of the present invention will be
described below in more detail, with reference to the accompanying
drawings, in which:
[0014] FIG. 1 depicts an exploded view of a display that is useful
for understanding the present invention;
[0015] FIG. 2 depicts a front view of a light emission layer that
is useful for understanding the present invention;
[0016] FIG. 3 depicts a front view of a first electrode that is
useful for understanding the present invention;
[0017] FIG. 4 depicts a front view of a second electrode that is
useful for understanding the present invention;
[0018] FIG. 5 is an enlarged section view of the light emission
layer of FIG. 3 and the electrodes of FIG. 2 and FIG. 4, each taken
along section line 5-5, in a stacked configuration;
[0019] FIG. 6 is an enlarged section view of the display of FIG. 1,
taken along section line 6-6, in a stacked configuration;
[0020] FIG. 7 is a flowchart that is useful for understanding the
present invention.
DETAILED DESCRIPTION
[0021] While the specification concludes with claims defining
features of the invention that are regarded as novel, it is
believed that the invention will be better understood from a
consideration of the description in conjunction with the drawings.
As required, detailed embodiments of the present invention are
disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention, which
can be embodied in various forms. Therefore, specific structural
and functional details disclosed herein are not to be interpreted
as limiting, but merely as a basis for the claims and as a
representative basis for teaching one skilled in the art to
variously employ the present invention in virtually any
appropriately detailed structure. Further, the terms and phrases
used herein are not intended to be limiting but rather to provide
an understandable description of the invention.
[0022] FIG. 1 depicts an exploded view of a display 100 that is
useful for understanding the present invention. The display 100 can
include a reflective display panel (hereafter "display panel") 102
from which visual information is presented. Such information can
include text, graphics, or any other information that may be
presented on a display. The display panel 102 can be, for example,
a liquid crystal display (LCD) panel, an electrophoretic display
(EPD) panel, a reflective type thin film transistor display panel,
a flip-dot display panel, or any other suitable reflective display
panel.
[0023] The display 100 also can include at least one light emission
layer 104 that generates and emits light, and is disposed in front
of the reflective display panel 102. In one arrangement, the light
emission layer 104 can be formed into a desired illumination
pattern. Such illumination pattern can encompass an area
substantially congruent with at least a visible portion 106 of a
front surface 108 of the display panel 102. The illumination
pattern need not illuminate portions of the display panel that will
not be viewed, for instance a portion 109 upon which display
drivers may be mounted, though the invention is not limited in this
regard. As used herein, the term "illumination pattern" means a
pattern defined by one or more regions from which light is
generated.
[0024] A front view of the light emission layer 104 is depicted in
FIG. 2. The illumination pattern can be defined by regions 210 of
the light emission layer 104 that comprise at least one component
211 which generates and emits light, and regions 212 in which the
component 211 is absent. The component 211 that generates and emits
light can be distributed over the area encompassed by the light
emission layer 104. Thus, the light can be generated and emitted in
a distributed fashion over such area.
[0025] In one arrangement, the component 211 of the light emission
layer 104 can comprise one or more light emitting diodes (LEDs).
For example, component 211 can comprise a p-type semiconducting
material and an n-type semiconducting material which interface to
form an emissive electroluminescent layer. Such materials are known
to those skilled in the art. In one arrangement, the LED can be
organic LED. In an organic LED, the emissive electroluminescent
layer may comprise a film of organic compounds. Advantageously, an
organic LED can be formed using a low cost inkjet printing process
or screen printing. Nonetheless, there are a myriad of materials
known to those skilled in the art that can be used to form an
emissive electroluminescent layer and the invention is not limited
in this regard.
[0026] Referring again to FIG. 1, a first electrode 113 and a
second electrode 114 can be disposed to contact either of the
opposing sides 116, 117 of the light emission layer 104 to supply
electrical energy to the light emission layer 104. In an
arrangement in which the light emission layer 104 comprises an LED,
the polarity of the voltage that is applied can be determined by
the orientation of the LED. For example, the electrode 113 can be
an anode applying a positive voltage to the LED if p-type
semiconducting material is disposed on the first side 116 of the
light emission layer 104. In such an arrangement, the electrode 114
can be a cathode applying a negative voltage if n-type
semiconducting material is disposed at the second side 117 of the
light emission layer 104. Similarly, the electrode 113 can be a
cathode applying negative voltage to the LED if n-type
semiconducting material is at the first side 116 of the light
emission layer 104, and the electrode 114 can be an anode applying
a positive voltage to the LED if p-type semiconducting material is
disposed at the second side 117 of the light emission layer 104. Of
course, if an organic LED is used, the anode and cathode can
interface with the suitable layers of organic material. Further, if
the light emission layer 104 is non-polarized, the polarity of the
electrodes 113, 114 may not be critical so long as sufficient
voltage potential is applied across the opposing sides 116, 117 of
the light emission layer 104.
[0027] FIG. 3 depicts a front view of the first electrode 113. In
one arrangement, the electrode 113 can comprise one or more
electrical conductors 318 arranged to precisely align with the
component(s) 211 of the light emission layer 104. For example, the
electrical conductors 318 can be arranged in the same illumination
pattern as the light emission layer 104.
[0028] If the electrical conductors 318 are opaque, the electrical
conductors 318 can be selected so as to have the minimum width
required for the electrical current anticipated to be flowing
through the electrical conductors 318. Accordingly, the electrical
conductors 318 will minimally interfere with the view of the
reflective display panel 102.
[0029] In another arrangement, the electrical conductors 318 can
comprise an electrically conductive material that is transparent
(e.g. optically clear). One example of such a material is titanium
tin oxide (ITO), although the invention is not limited in this
regard and any other suitable conductor that is transparent may be
used.
[0030] An electrical connector 320 can be electrically connected to
the electrode 113 so as to provide the suitable electrical current
to the electrode.
[0031] FIG. 4 depicts a front view of the second electrode 114. The
second electrode 114 can comprise one or more electrical conductors
422 arranged to precisely align with the component(s) 211 of the
light emission layer 104. For example, the electrical conductors
422 can be arranged in the same illumination pattern as the light
emission layer 104.
[0032] In one arrangement, the electrical conductors 422 can
comprise an electrically conductive material that is transparent,
for instance ITO. Thus, the electrical conductors 422 can minimally
affect light radiated by the light emission layer 104 toward the
display panel 102.
[0033] An electrical connector 424 can be electrically connected to
the electrode so as to provide suitable electrical current to the
electrode.
[0034] FIG. 5 is an enlarged section view of the light emission
layer 104 and the first and second electrodes 113, 114, each taken
along section line 5-5. Other layers can be stacked with the light
emission layer 104 and the electrode 113, 114 to form the display,
but such layers are not shown in FIG. 5 for the purpose of clarity.
Further, FIG. 5 is not indicative of any specific sequence in which
layers of the display should be stacked.
[0035] The light emission layer 104 and the first and second
electrodes 113, 114 can be stacked such that the electrodes 113,
114 interface with the opposing sides 116, 117 of the light
emission layer 104 and component(s) 211, respectively. Light 526
generated by the light emission layer 104 can radiate in multiple
directions. In an arrangement in which the electrical conductor 318
is opaque, a portion 528 of such light 526 incident on the
electrical conductor 318 can be reflected toward the display panel
102. If the electrical conductor 422 is transparent, the reflected
light 528 can pass through the electrical conductor 422 with little
or no reflection and/or diffraction.
[0036] Referring again to FIG. 1, the display 100 optionally can
include a light diffusion layer 130 to diffuse light reflected off
of the display panel 102. Such an arrangement can aid in masking
the electrical conductors 318 if such conductors are opaque. The
light diffusion layer 130 can comprise a light diffusing material
131, for example silicon dioxide, applied a substrate 132. Such
substrates are known to the skilled artisan.
[0037] The display 100 further can include a first transparent
layer 134 and a second transparent layer 136, each of which may
comprise a suitable transparent substrate 138, 140, respectively,
such as a suitable resin or glass. The transparent layer 134 can be
positioned behind the electrode 114, and serve to protect the
electrodes 113, 114 and the light emission layer 104. Similarly,
the transparent layer 136 can be positioned over the light
diffusion layer 130 to provide an outermost surface of the display
100 that serves to protect the display components. In another
arrangement, in lieu of using the light diffusion layer 130, the
light diffusing material 131 can be applied to the transparent
layer 136, for instance to an inner side 141.
[0038] FIG. 6 is an enlarged section view of the display 100 of
FIG. 1, taken along section line 6-6. The display panel 102, first
transparent layer 134, second electrode 114, light emission layer
104, first electrode 113, light diffusion layer 130 and second
transparent layer 136 can be arranged in a stack to form the
display 100. In particular, the light emission layer 104 can be
disposed in front of the display panel 102. Further, the first
electrode 113 can be disposed on the first side 116 of the light
emission layer 104, opposite the second side 117 facing the display
panel 102. The second electrode 114 can be disposed on the second
side 117 of the emission layer 104.
[0039] Further, the electrical connectors 320, 424 can be disposed
such that they are accessible to be connected to a voltage source.
For instance, the electrical connectors 320, 424 can extend beyond
an edge 642 of the stacked components.
[0040] Together, the first transparent layer 134, second electrode
114, light emission layer 104, first electrode 113, light diffusion
layer 130 (optional), second transparent layer 136, and electrical
connectors 320, 424 can form a self emission device 644. The self
emission device 644 can engage, or otherwise be positioned
proximate to, the display panel 102.
[0041] In operation, voltage can be applied across the connectors
320, 424, thereby applying voltage across light emission layer 104,
thereby causing the light emission layer 104 to generate and emit
light. In consequence, light 526 can radiate to, and reflect off
of, the display panel 102. The reflected light 646 can convey
visual information presented on the display panel 102 beyond an
upper surface 648 of the self emission device 644. As noted, at
least a portion of light 526 propagating directly from the light
emission layer 104 to the first electrode 113 can be reflected by
the first electrode 113, toward a lower side 650 of the self
emission device 644, and onto the display panel 102.
[0042] The display 100 can be a component of a telephone, a
personal digital assistant, a computer, a television, a video
monitor, a stand alone display, a portable device, an appliance, a
vehicle, an aircraft, a vessel, equipment, and so on. The invention
is not limited to these examples, however, and the display 100 can
be a component of any device which having a display.
[0043] FIG. 7 is a flowchart presenting a method 700 that is useful
for understanding the present invention. At step 702 a first
electrode can be deposited on a first substrate. The first
substrate can be a translucent layer or a transparent layer.
[0044] At step 704, a light emission layer can be deposited on the
first electrode. For instance, a first semiconductor (e.g. a p-type
semiconductor) can be deposited on the first electrode, and a
second semiconductor (e.g. an n-type semiconductor) can be
deposited on the first semiconductor to form an emissive
electroluminescent layer.
[0045] At step 706, a second electrode can be deposited on the
light emission layer. As noted, the first and second electrodes can
be configured to provide electrical energy to the light emission
layer.
[0046] In one arrangement, deposition of one or more layers can be
performed using an inkjet printing process. For example, the layers
can be deposited to form a desired illumination pattern. In another
arrangement, deposition of one or more layers can be performed
using screen printing. Etching techniques also can be implemented.
For example, the various layers can be deposited over an entire
side of the first substrate in the appropriate order. An etching
process then can be implemented to remove portions of such layers
where desired to expose the first substrate. The remaining portions
of the electrode and light emission layers can form the desired
illumination pattern. It should be noted that a myriad of suitable
deposition and etching techniques are known to those skilled in the
art, and such techniques are within the scope of the present
invention.
[0047] At step 708, a second substrate can be positioned over the
second electrode. The second substrate can be transparent. In an
arrangement in which the first substrate is transparent, the first
substrate, the first electrode, the light emission layer, the
second electrode, and the second substrate together can form a
self-emission device. In an arrangement in which the first
substrate is translucent, a third substrate can be placed over the
first substrate on a side opposite the first electrode. In such an
arrangement, the third substrate can be included in the
self-emission device. At step 710, the self emission device can be
placed over a reflective display panel.
[0048] The flowchart and diagrams in the figures illustrate the
architecture, functionality, and operation of possible
implementations of systems and methods according to various
embodiments of the present invention. It should also be noted that,
in some alternative implementations, the functions noted in the
block may occur out of the order noted in the figures. For example,
two blocks shown in succession may, in fact, be executed
substantially concurrently, or the blocks may sometimes be executed
in the reverse order, depending upon the functionality
involved.
[0049] The terms "a" and "an," as used herein, are defined as one
or more than one. The term "plurality," as used herein, is defined
as two or more than two. The term "another," as used herein, is
defined as at least a second or more. The terms "including" and/or
"having," as used herein, are defined as comprising (i.e. open
language).
[0050] This invention can be embodied in other forms without
departing from the spirit or essential attributes thereof.
Accordingly, reference should be made to the following claims,
rather than to the foregoing specification, as indicating the scope
of the invention.
* * * * *